Children, especially girls, who own smartphones before they are 13 years old may have worse mental health outcomes when they're older, a new study suggests. The study, published Sunday in the Journal of Human Development and Capabilities, analyzed self-reported questionnaire results from more than 100,000 young adults between the ages of 18 and 24.

ABC News' Dr. Tara Narula breaks down a new report linking smartphone use before age 13 to poorer mental health outcomes in early adulthood.